In these studies, we will define the patterns and natural history of insulin secretion in kidney-pancreas transplant recipients. The tranplanted pancreas is a unique human model in which to study beta cell function since the pancreas is situated in an abnormal ana tomic site, drains into the systemic rather than the portal circulation, and has been severed from its central neurological connections. The proposed studies will define quantitative and qualitative alterations in insulin secretion which occur in these patients.